Post by: koolray09 on November 13, 2015, 11:37:30 am
The cover which allows access to the torque converter, has large holes and the cover has two places on the bottom where to mount support brackets that come from the engine. The transmission originally had small bolt holes to receive a tin cover plate, three of them were drilled out to accept a larger bolt which was required to marry the torque cover plate.
I am being told by a GM tech who has long time experience with transmissions that in order to be a true 4x4 transmission case, their should be large bolt holes in the case to receive the torque convertor cover. The small tapped hole probably recieves a 3/16 or 1/4 bolt, the large receives something close to a 3/8 inch bolt.
How the heck does a guy know ? I've seen hundreds of pictures on google that show guys proudly showing off their rebuilt turbo 350 transmission for 4x4 application - no tail, shaft sticks out 1" past housing - and the bolt holes for the torque cover are small bolt holes.
I did see one "K" case - It look just like the 350 case I have and had a K in large letter, top right of case bell housing. Is this the TRUE 4x4 case I seek ? I know that this case is thicker.
how does a guy know if a transmission is a true 4x4 or simply a reused 2wd case ?
Is there such a thing as a true 4x4 case ? does the main body of all 4x4 cases look like the main body of a 2wd ? do the bolt holes at the converter cover a dead giveaway ? inquiring minds want to know. Is there a definitive answer to this question ?
Pictures are always appreciated.
Post by: 1967KaiserM715 on November 13, 2015, 04:57:25 pm
I don't believe bolt size changed alot, 1/4 to 5/16 maybe, but would use an aluminum flex cover, rather then stamped steel
the HD trannys had several more ribs in the bell housing, and a thicker case
beyond that, if it bolts up to a transfer case it is 4x4, wether it was built with a 2wd case(just need to swap tailshaft)
Post by: Irish_Alley on November 13, 2015, 10:31:48 pm
Post by: koolray09 on November 14, 2015, 10:22:43 am
I have NEVER seen a 350 case marked HD. and I've looked at a few. They all appear to be cases with four small bolt ups for a tin dust cover, which I am told is a dead give away that the case came off a 2wd application. Can anybody out there verify this information. The matter is not whether I can use the 2wd case for a 4x4 application, the matter is whether or not a th350 case for a 4x4 application is different, and if so, in what way. This is the heart of the matter I need to answer as it will help me make a buying decision.
the 4x4 application has two supporting arms that marry to the bottom of the dust cover, the other ends bolt to the engine either side, below the motor mounts, for added support. From what I gather, you can use the 2wd case for a 4x4 application, but in order to reuse the beefy dust cover, you have to drill out the four small bolts holes and drill in two more. the material at this point is thinner and more prone to breakage. the th350 K marked ones have thicker material at this junction.
Post by: enaberif on November 14, 2015, 11:35:44 am
If you have a TH350 the dust shield isn't going to make a difference between a 2wd and a 4wd th350.
There are differences between a 2wd and 4wd TH350 like the output shaft but that is about it. I have a TH350 with a dust shield that only bolts up with 2 bolts and have never seen a 4 bolt dust shield ever.
And I have a 4wd Th350
Post by: VileZambonie on November 14, 2015, 12:43:18 pm
Post by: rich weyand on November 14, 2015, 01:11:05 pm
Post by: Irish_Alley on November 14, 2015, 02:55:13 pm
I ran across a transmission with "K" markings, modulator sticks out the back like all TH350s, has a 32 spline and it has six large opening bolt holes to recieve the dust cover. My dust cover has 6 large openings. This is not a 700 and it has the K marking. I am told this a more desirable transmission as the case is thicker and the 32 spline is more desired over the 27.
I have NEVER seen a 350 case marked HD. and I've looked at a few. They all appear to be cases with four small bolt ups for a tin dust cover, which I am told is a dead give away that the case came off a 2wd application. Can anybody out there verify this information. The matter is not whether I can use the 2wd case for a 4x4 application, the matter is whether or not a th350 case for a 4x4 application is different, and if so, in what way. This is the heart of the matter I need to answer as it will help me make a buying decision.
the 4x4 application has two supporting arms that marry to the bottom of the dust cover, the other ends bolt to the engine either side, below the motor mounts, for added support. From what I gather, you can use the 2wd case for a 4x4 application, but in order to reuse the beefy dust cover, you have to drill out the four small bolts holes and drill in two more. the material at this point is thinner and more prone to breakage. the th350 K marked ones have thicker material at this junction.
the th350 was never a 32 spline output shaft it only came in 27
take some pictures
Post by: enaberif on November 14, 2015, 03:18:46 pm
Post by: HAULIN IT on November 14, 2015, 07:07:19 pm
I've had 2wd trans cases in both of my 4x4's (to use the multi-bell TH350 case) without a problem. Look at it this way...What is wrong with the tranny from the truck? The insides are wore (metal in the pan) not a broken case! Do I think the braces are a good idea...yea, but not needed for the average truck.
My Thoughts, Lorne
Post by: koolray09 on November 14, 2015, 08:00:33 pm
I have a 1978 K-10 350/TH350/NP203 sitting in the garage. I believe the trans and xfer case are original. You tell me what pics you want, and I'll take them.
take pictures of the th350 where the dust cover bolts to the transmission. top down view is ok.
Post by: koolray09 on November 14, 2015, 08:24:04 pm
I misplaced my camera, else I would take pictures of my dust cover, it is cast aluminum and it is thick, it is definitely not tin and thin.
Post by: koolray09 on November 14, 2015, 08:28:10 pm
Post by: enaberif on November 14, 2015, 08:39:09 pm
Post by: Irish_Alley on November 14, 2015, 08:55:15 pm
Post by: enaberif on November 14, 2015, 09:11:37 pm
Post by: 1967KaiserM715 on November 14, 2015, 09:39:26 pm
Sent from my iPhone using Tapatalk
Post by: koolray09 on November 15, 2015, 08:05:04 am
Very interesting! What are the numbers/letters on either the governor cover or the round cover on the passenger side.
The transmission is not with me...those are pictures sent to me by current owner.
Post by: koolray09 on November 15, 2015, 09:04:28 am
maybe i never paid that much attention to my th350s about the k lol. but it shouldnt be a 32 spline and if it is you will need to get an adapter to mate your t case to the new trans output shaft.
The transmission was removed from a running/driving truck. I ran across the ad for the tranny some weeks ago and did some research on the "K" marked cases, I remember reading something about them having a 32 spline out put shaft, and that this was more desirable. I have tried to locate that website again and have been unable to do so.
I have been told by a transmission tech that it is possible they put the output spline from a 700 into this case to marry it up to a transfer case with 32 spline.
Post by: Irish_Alley on November 15, 2015, 04:35:53 pm
Post by: Jason S on November 15, 2015, 05:54:37 pm
The "K" or "HD" TH-350 case seems to be late 70's-up and may or may not be marked. It would have thicker material in the dust shield area for bolting on a cast dust cover. That dust shield would have bosses to bolt strut rods that tie to the engine mounts. Information on the earlier 70's TH-350 doesn't indicate this was available.
From the '79 manual shows the location of the strut rods that run from the cast cover to the engine mounts.
(https://lh3.googleusercontent.com/-uqnGos97yS0/VkkWESb4gpI/AAAAAAAABBM/VEa4Hu3OlC0/s400-Ic42/SAM_6308.JPG)
Also from the '79 manual, the brace rods for the transfer case.
(https://lh3.googleusercontent.com/-fhgfWyAHBd4/VkkWF0TeUKI/AAAAAAAABBU/krM_lSSK74k/s400-Ic42/SAM_6309.JPG)
And from the '73 manual, the braces used
(https://lh3.googleusercontent.com/-pcXNDPcwTVg/VkkWEWdHRNI/AAAAAAAABBo/exEdmnJ-oJo/s400-Ic42/SAM_6307.JPG)
Post by: Engineer on November 18, 2015, 09:21:35 pm
Post by: AZ87V10 on November 18, 2015, 11:11:49 pm
Post by: koolray09 on November 26, 2015, 04:46:05 pm
Saturday November 27 I should have my rebuilt transmission in my hand. Then work to marry to np203 - gasket on order. Any volunteers to help me reinstall the beastly assembly - it is crazy heavy and unwieldy. what - no volunteers ? Guess I will have to deploy physics and gravity to help me reinstall the unit. I have a plan.
Post by: LTZ C20 on November 26, 2015, 05:58:45 pm
Post by: frotosride on November 26, 2015, 06:59:54 pm
Post by: Engineer on November 26, 2015, 08:14:23 pm
I have found that it is easier to install the transmission if you pick the truck up and flip it upside down and lay it back down on the cab roof. Then you can pic the trans and t-case up, flip them over, drop them in, bolt then up and pick the truck back up and flip it back onto it's wheels and put all the fluid in and hook up the rest of the stuff. Just make sure you put one of the nice guest bathroom towels on the ground to rest the cab roof on so you don't scratch the paint!
I used to do it that way but I got tired of getting all greasy from laying on my belly trying to reach the two bellhousing bolts that are behind the distributor.
Post by: Jrgunn5150 on November 26, 2015, 09:01:37 pm
Post by: Irish_Alley on November 26, 2015, 09:03:22 pm
Post by: LTZ C20 on November 26, 2015, 10:04:47 pm
I used to do it that way but I got tired of getting all greasy from laying on my belly trying to reach the two bellhousing bolts that are behind the distributor.
[/quote]
Lol I here ya, there are trade offs to this way. Like filling the trans fluid, the fill tube becomes a drain tube!
Post by: Jason S on November 27, 2015, 10:59:13 am
Saturday November 27 I should have my rebuilt transmission in my hand. Then work to marry to np203 - gasket on order. Any volunteers to help me reinstall the beastly assembly - it is crazy heavy and unwieldy. what - no volunteers ? Guess I will have to deploy physics and gravity to help me reinstall the unit. I have a plan.I think one of the adjustable transmission jacks is worth it - if even only for stabbing a 203 once...
Post by: LTZ C20 on November 27, 2015, 12:19:50 pm
Those are worth every penny. I've done it with and without, with is much better.Saturday November 27 I should have my rebuilt transmission in my hand. Then work to marry to np203 - gasket on order. Any volunteers to help me reinstall the beastly assembly - it is crazy heavy and unwieldy. what - no volunteers ? Guess I will have to deploy physics and gravity to help me reinstall the unit. I have a plan.I think one of the adjustable transmission jacks is worth it - if even only for stabbing a 203 once...